Supplementation of vitamin D may safely reduce the overall risk for acute respiratory infection compared with placebo, but there is little reduction in the risk and relevance of these findings to coronavirus disease by 2019 ( COVID-19) is unknown and requires further investigation. This is according to research published in Lancet Diabetes Endocrinology.
Since the onset of the COVID-19 pandemic, interest in the role of vitamin D in reducing acute respiratory infections has grown. The results of randomized controlled trials, however, were heterogeneous and variable, with some demonstrating protection and others reporting findings to be ineffective. The results of a 2017 meta-analysis demonstrated the potential protective effect of vitamin D supplementation. The researchers sought to elucidate the results by conducting a new systematic review and meta-analysis of the study conducted from December 31, 2015.
The primary outcome of the study was the proportion of patients with one or more respiratory tract infections (high, low, or unclassified location). The second outcome included the proportion of participants who experienced one or more high or low respiratory infections, emergency department visits, hospitalization, or both for a severe respiratory infection, death due to severe respiratory infections or respiratory failure, antibiotic use, absence from school or work, severe adverse events, death, and potential adverse reactions to vitamin D.
The analysis included 46 studies representing 75,541 patients. Thirty studies compared the effects of the vitamin D regimen with placebo, 5 compared the higher dose and dose vitamin D with placebo groups, and 6 compared the effects of the higher dose vitamin D with placebo. have the lowest dose vitamin D regimens.
Primary outcome data were obtained for 98.1% of the 49,419 available participants.
In 35 studies that measured baseline concentrations of 25 (OH) D, mean levels ranged from 18.9 to 90.9 nmol / L. Throughout the study, vitamin D was delivered via variable routes, including oral dosing, weekly dose, bolus dosing once per month to once every 3 months, and combination bolus and daily application.
A significantly lower proportion of participants taking vitamin D supplements had 1 or more respiratory tract infections compared with those taking placebos (61.3% vs 62.3%; odds ratio [OR], 0.92; 95% CI, 0.86–0.99). The heterogeneity effect for this data is moderate (I2= 35.6%).
For the second comparison of high versus low -dose vitamin D supplementation, no significant difference in the proportion of at least one respiratory infection was observed among the groups of participants (68.2% vs 64.6%; OR, 0.87; 95% CI, 0.73-1.04; I2= 0.0%).
To investigate the factors of effect heterogeneity for the primary comparison (vitamin D vs placebo), the researchers combined examined 2 factors at participant level (baseline 25 (OH) D concentration and age) and 4 factors test level (dose, dose frequency, duration of the test, and presence or absence of airway disease). Four of these factors — baseline 25 (OH) D concentration, dose, dose frequency, and duration of the test — were taught in the study protocols and two — age and presence or absence of airway infections — were exploratory analysis.
Compared with the placebo groups, there was no significant effect of increasing vitamin D on the risk of having 1 or more acute respiratory infections in participants with baseline 25 (OH) D concentrations that were shorter. at 25 nmol / L, 25 to 49.9 nmol / L, 50 to 74.9 nmol / L, or more than 75 nmol / L (ORs, 0.81, 1.04, 0.88, 0.76, and 1.00, respectively).
A significant protective effect of vitamin D supplementation was seen in the risk for developing one or more respiratory tract infections compared with placebo, especially in trials where vitamin D was given daily (O 0.78). compared with weekly application or bolus increase once a month or once every 3 months (ORs, 0.97 and 0.98).
Significant protective effects were also found against the risk of having one or more acute respiratory infections vs placebo in trials not limited to participants with asthma or chronic obstructive pulmonary disease (COPD).
The meta-analysis for the second outcome included only the results of the placebo-controlled trials. Without considering the participants ’factors or test level, vitamin D supplement did not show a significant effect on the proportion of participants who experienced 1 or more high or low respiratory infections, used antibiotics to treat an infection, reported being absent from school or work, or being admitted at the hospital, or who went to the emergency department.
Limitations of the study accompanied the analysis of the overall trial level, rather than the individual participant level due to the need for outcomes in the face of the COVID-19 pandemic, lack of participant-level data. of race, ethnicity, or obesity as potential impact-changes, and an inability to account for other factors that may influence the protective effect of augmentation.
“This updated meta-analysis… showed a significant overall protective effect of this intervention compared to a placebo control,” the researchers wrote. “Contrary to the findings of our previous meta-analysis of the individual participant level, we did not find a protective effect… among participants with the lowest baseline 25 (OH) D concentration. “
The most beneficial use of vitamin D dose is the commonly used dose (400-1000 IU) for up to 12 months. The relevance of these findings to COVID-19 is unknown and requires further investigation, ”they concluded.
Disclosure: Several study authors have declared relevance to the pharmaceutical industry. Please see the original reference for a full list of what the authors have revealed.
Jolliffe DA, Camargo Jr. CA, Sluyter JD, et al. Vitamin D supplementation to prevent acute respiratory infections: A systematic review and meta-analysis of combined data from randomized controlled trials. Published online March 30, 2021. Lancet Diabetes Endocrinol. doi: 10.1016 / S2213-8587 (21) 00051-6.
This article originally appeared Endocrinology Consultant